Most existing precessional devices are passive devices that require a deflecting torque from an external source to generate a precessional torque. A common example of this type of precessional device is the gyroscopic heading indicator used for aviation navigation. The spinning rotor inside such a device does not generate precessional torque on its own, rather, it simply responds to the torque exerted on it (by the directional changes of the aircraft) by maintaining its original heading relative to the magnetic compass.
In contrast to this passive type of precessional device, U.S. Pat. No. 6,401,556 issued to Hamady on Jun. 11, 2002, herein incorporated by reference in its entirety, discloses a precessional device which generates a precessional torque without requiring an externally inputted deflecting torque. The disclosed device employs rotors which precess along a circular race or track. Axles run through each rotor making contact at either end with the surface of the tracks. The rotors' spin rate, ωs, is directly proportional to the rotational velocity, ωr, which is defined as the frequency of the rotors' precession around the track. The relationship between ωr and ωs is determined by the ratio of the diameter of the axle tips such that ωs=ωr dtrack/daxle. The practical implication of this direct relationship is that the rotor speed (and resulting net precessional output torque) can not be increased without a corresponding increase in the oscillation frequency (Hz) of the net output torque. This limits the devices usefulness in applications such as resistive exercise where high resistance is often associated with slower movements and low resistance exercise is often associated with faster movements. Therefore, there remains a need for a device where ωs may be increased beyond the constraints defined by ωs=ωr dtrack/daxle, including but not limited to, a device where ωs and ωr may be controlled independently of each other.